I know you found it already, but I'll still point out that there is a link directly to the post in the quote (the

icon).
It's also on the first page for people like me, who have 40 posts per page. ^^
But yeah, obviously one must take care not to get involved with the RMTing kind, but I don't think it should be too difficult. I could almost bet on them referring to really obnoxious type of advertising when they speak of “disrupting to other players”, and by that I mean repeating the advertisement between short intervals, and doing it for extended periods of time. Also known as
spamming.
As far as I know, to this day, they have not stated that selling services like
fell cleaving is forbidden, so I would not be too worried about it unless I were one of the you know what kind.
That is, of course, just my opinion and view on the matter.